1	package antlr;
2	
3	/**
4	 * <b>SOFTWARE RIGHTS</b>
5	 * <p>
6	 * ANTLR 2.5.0 MageLang Institute, 1998
7	 * <p>
8	 * We reserve no legal rights to the ANTLR--it is fully in the
9	 * public domain. An individual or company may do whatever
10	 * they wish with source code distributed with ANTLR or the
11	 * code generated by ANTLR, including the incorporation of
12	 * ANTLR, or its output, into commerical software.
13	 * <p>
14	 * We encourage users to develop software with ANTLR. However,
15	 * we do ask that credit is given to us for developing
16	 * ANTLR. By "credit", we mean that if you use ANTLR or
17	 * incorporate any source code into one of your programs
18	 * (commercial product, research project, or otherwise) that
19	 * you acknowledge this fact somewhere in the documentation,
20	 * research report, etc... If you like ANTLR and have
21	 * developed a nice tool with the output, please mention that
22	 * you developed it using ANTLR. In addition, we ask that the
23	 * headers remain intact in our source code. As long as these
24	 * guidelines are kept, we expect to continue enhancing this
25	 * system and expect to make other tools available as they are
26	 * completed.
27	 * <p>
28	 * The ANTLR gang:
29	 * @version ANTLR 2.5.0 MageLang Institute, 1998
30	 * @author Terence Parr, <a href=http://www.MageLang.com>MageLang Institute</a>
31	 * @author <br>John Lilley, <a href=http://www.Empathy.com>Empathy Software</a>
32	 */
33	/**The context needed to add root,child elements to a Tree.  There
34	 * is only one alternative (i.e., a list of children).  We subclass to
35	 * specialize. MakeGrammar.addElementToCurrentAlt will work correctly
36	 * now for either a block of alts or a Tree child list.
37	 *
38	 * The first time addAlternativeElement is called, it sets the root element
39	 * rather than adding it to one of the alternative lists.  Rather than have
40	 * the grammar duplicate the rules for grammar atoms etc... we use the same
41	 * grammar and same refToken behavior etc...  We have to special case somewhere
42	 * and here is where we do it.
43	 */
44	class TreeBlockContext extends BlockContext {
45		protected boolean nextElementIsRoot = true;
46	
47	
48		public void addAlternativeElement(AlternativeElement e) {
49			TreeElement tree = (TreeElement)block;
50			if ( nextElementIsRoot ) {
51				tree.root = (GrammarAtom)e;
52				nextElementIsRoot = false;
53			}
54			else {
55				super.addAlternativeElement(e);
56			}
57		}
58	}
59